<tr>
    <td colspan="2">
        <div class="custom-form-error">
            <?php echo $form[$campo]->renderError() ?>
        </div>
    </td>
</tr>
<tr>
    <td>
        <?php if ($form->getValidator($campo)->getOption('required')): ?>
            <?php echo $form[$campo]->renderLabel(null, array('class' => 'required')) ?>:
        <?php else:?>
                <?php echo $form[$campo]->renderLabel() ?>:
        <?php endif;?>
    </td>
    <td>
        <?php $class = $form[$campo]->renderError() ? 'content form-error' : 'content' ?>
        <div class="<?php echo $class;?>">
            <?php echo $form[$campo]->render(array('class'=>'input'))?>
        </div>
    </td>
</tr>